Electrical heating cartridges can comprise at least one electrical heating coil and a thermocouple element mounted inside a jacket, preferably of metal such cartridges can be used for heating electrical switch boxes, articles in which they are inserted, etc.
The electrical heating coil or coils and thermocouple element are imbedded in a packed insulating material with clearance from each other and from the preferably metal jacket. The electrical lead conductors of the electrical heating coils and of the thermocouple element are fed out of one end of the heating cartridge, the heating coil has a first strand beginning at a first end piece and being fed toward a second end piece of the closed end of the electrical heating cartridge opposite to the first end piece and a second strand connected to the first strand and guided back to the first end piece. Advantageously the thermocouple element is oriented substantially parallel to the electrical heating coil.
In the known electrical heating cartridges, as taught in German utility model DE-GM No. 79 32 598, the position of attachment of the thermocouple legs oriented at an acute angle to each other at the measuring point is on the metal base of the jacket which closes the cartridge at the closed or bottom end and the electrical heating coil has a comparatively large clearance from the aforementioned base being set back therefrom.
Because of this arrangement relatively large regions of the cartridge may not be directly heated.
The measuring point of the thermocouple element is positioned with a comparatively large clearance from the electrical heating coil, so that the heating effect of the electrical heating coil can be determined by the thermocouple element only with a significant time delay.
Consequently the cartridge in the vicinity of the heating coil may have already exceeded the desired preselected maximum temperature before the thermocouple element and the control mechanism influenced by it can react.